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Woolcott, Orison O., Till Seuring, and Oscar A. Castillo. Lower prevalence of body fat-defined obesity at higher altitudes in Peruvian adults. High Alt Med Biol. 24:214-222, 2023. Background: Previous studies have reported a lower prevalence of obesity (defined as a body mass index [BMI] ≥30 kg/m2) in populations from higher altitudes. Since BMI does not distinguish fat mass and fat-free mass, it is unclear whether there is an inverse association between altitude and body fat-defined obesity. Methods: We performed an analysis of cross-sectional data to examine the association between altitude and body fat-defined obesity (as opposed to BMI-defined obesity) using individual-level data from a nationally representative sample of the Peruvian adult population living between 0 and 5,400 m altitude. Body fat-defined obesity was diagnosed using the relative fat mass (RFM), an anthropometric index validated to estimate whole-body fat percentage. RFM cutoffs for obesity diagnosis were ≥40% for women and ≥30% for men. We utilized Poisson regression to estimate the prevalence ratio and confidence intervals (CIs) as the measure of the association, adjusting for age, cigarette use, and diabetes. Results: Analysis comprised 36,727 individuals (median age, 39 years; 50.1% women). In rural areas, for a one-km increase in altitude, the prevalence of body fat-defined obesity decreased by 12% among women (adjusted prevalence ratio: 0.88; 95% CI, 0.86 - 0.90; p < 0.001) and 19% among men (adjusted prevalence ratio: 0.81; 95% CI, 0.77 - 0.86; p < 0.001), on average, when all the other variables were held constant. The inverse association between altitude and obesity was less strong in urban areas than in rural areas but remained significant among women (p = 0.001) and men (p < 0.001). However, the relationship between altitude and obesity in women who live in urban areas appears to be nonlinear. Conclusions: In Peruvian adults, the prevalence of body fat-defined obesity was inversely associated with altitude. Whether this inverse association is explained by altitude per se or confounded by socioeconomic or other environmental factors, or differences in race/ethnicity or lifestyle, warrants further investigation.

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Diabetes is associated with severe COVID-19 and mortality. The aim of the present study was to determine the effect of age on the association between diabetes and mortality in patients with laboratory-confirmed COVID-19 in Mexico. This retrospective cohort study involved patients aged 20 years or older with symptoms of viral respiratory disease who were screened for SARS-CoV-2 infection across the System of Epidemiological Surveillance of Viral Respiratory Disease in Mexico from January 1 through November 4, 2020. Cox proportional-hazard regression was used to calculate the hazard ratio for 28-day mortality and its 95% confidence interval (CI). Among 757,210 patients with COVID-19 (outpatients and inpatients), 120,476 (16%) had diabetes and 80,616 died. Among 878,840 patients without COVID-19 (those who tested negative for SARS-CoV-2 infection), 88,235 (10.0%) had diabetes and 20,134 died. Among patients with COVID-19, diabetes was associated with a hazard ratio for death of 1.49 (95% CI 1.47-1.52), adjusting for age, sex, smoking habit, obesity, hypertension, immunodeficiency, and cardiovascular, pulmonary, and chronic renal disease. The strength of the association decreased with age (trend test: P = 0.004). For example, the adjusted hazard ratio for death was 3.12 (95% CI 2.86-3.40) for patients 20-39 years of age; in contrast, the adjusted hazard ratio of death for patients 80 years of age or older was 1.11 (95% CI 1.06-1.16). The adjusted hazard ratios were 1.66 (95% CI 1.58-1.74) in outpatients and 1.14 (95% CI 1.12-1.16) in inpatients. In hospitalized patients 80 years of age or older, no association was observed between diabetes and COVID-19-related mortality (adjusted hazard ratio: 1.03; 95% CI 0.98-1.08). Among patients without COVID-19, the adjusted hazard ratio for death was 1.78 (95% CI 1.73-1.84). In conclusion, in adult patients with COVID-19 in Mexico, the risk of death associated with diabetes decreased with age. No association between diabetes and mortality was observed among inpatients 80 years of age or older. Our findings should be verified in other populations.

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Woolcott, Orison O., and Richard N. Bergman. Mortality attributed to COVID-19 in high-altitude populations. High Alt Med Biol. 21:409-416, 2020. Background: Since partial oxygen pressure decreases as altitude increases, environmental hypoxia could worsen Coronavirus Disease 2019 (COVID-19) patient's hypoxemia. We compared COVID-19 mortality at different altitudes. Methods: Retrospective analysis of population-level data on COVID-19 deaths was conducted in the United States (1,016 counties) and Mexico (567 municipalities). Mixed-model Poisson regression analysis of the association between altitude and COVID-19 mortality was conducted using individual-level data from 40,168 Mexican subjects with COVID-19, adjusting for multiple covariates. Results: Between January 20 and April 13, 2020, mortality rates were higher in U.S. counties located at ≥2,000 m elevation versus those located <1,500 m (12.3 vs. 3.2 per 100,000; p < 0.001). In Mexico, between March 13 and May 13, 2020, mortality rates were higher in municipalities located at ≥2,000 m versus those located <1,500 m (5.3 vs. 3.9 per 100,000; p < 0.001). Among Mexican subjects younger than 65 years, the risk of death was 36% higher in those living at ≥2,000 m versus those living at <1,500 m (adjusted incidence rate ratio [IRR]: 1.36; confidence interval [95% CI], 1.05-1.78; p = 0.022). Among Mexican men, the risk of death was 31% higher at ≥2,000 m versus that at <1,500 m (adjusted IRR: 1.31; 95% CI, 1.03-1.66; p = 0.025). No association between altitude and COVID-19 mortality was found among Mexican women or among Mexican subjects 65 years of age and older. Conclusions: Altitude is associated with COVID-19 mortality in men younger than 65 years.

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OBJECTIVE: To determine the association between altitude and obesity in a nationally representative sample of the Peruvian adult population. METHODS: This is a cross-sectional analysis of publicly available data from the Food and Nutrition National Center (CENAN, Peru), period 2009-2010. The Prevalence ratio of obesity and abdominal obesity was determined as a measure of association. Obesity and abdominal obesity were diagnosed based on direct anthropometric measurements. RESULTS: The final data set consisted of 31,549 individuals ≥20 years old. The prevalence ratio of obesity was as follows: 1.00 between 0 and 499 m (reference category), 1.00 (95% confidence interval 0.87-1.16) between 500-1,499 m, 0.74 (0.63-0.86) between 1,500-2,999 m, and 0.54 (0.45-0.64) at ≥3,000 m, adjusting for age, sex, self-reported physical activity, out-migration rate, urbanization, poverty, education, and geographical latitude and longitude. In the same order, the adjusted prevalence ratio of abdominal obesity was 1.00, 1.01 (0.94-1.07), 0.93 (0.87-0.99), and 0.89 (0.82-0.95), respectively. We found an interaction between altitude and sex and between altitude and age (P < 0.001, for both interactions) on the association with obesity and abdominal obesity. CONCLUSIONS: Among Peruvian adult individuals, we found an inverse association between altitude and obesity, adjusting for multiple covariates. This adjusted association varied by sex and age.

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La prevalencia de obesidad a nivel mundial continúa en ascenso. La obesidad es un factor de riesgo para diversas enfermedades incluyendo diabetes tipo 2, enfermedades cardiovasculares y cáncer. Por lo menos 140 millones de personas en el mundo viven a una altitud superior a los 2500m. Interesantemente, existe evidencia de un incremento en el metabolismo de la glucosa en la altura, incluyendo una menor resistencia a la insulina en sujetos no obesos. Ya que la resistencia a la insulina, caracterizada por una disminución en la captación de glucosa a nivel de tejidos periféricos, es una manifestación frecuente en sujetos obesos, se especula que existiría una menor prevalencia de obesidad en la altura. Por lo tanto, el objetivo del presente artículo es revisar los estudios de prevalencias de sobrepeso y obesidad en poblaciones adultas de la altura.

The global prevalence of obesity is increasing significantly. Obesity is a risk factor for many diseases including type 2 diabetes, cardiovascular diseases and cancer. At least 140 million people in the world live at high altitude, above 2500m. Interestingly, there is evidence of an increase in glucose metabolism at high altitude, including less insulin resistance in nonobese subjects. Since insulin resistance, characterized by a decrease in peripheral glucose uptake, is highly prevalent in obesity, it has been speculated that the prevalence of obesity would be lower at high altitude. Therefore, the aim of this article is to review the prevalence studies of overweight and obesity in adult populations from high altitude.

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Objetivo: determinar la respuesta del sistema antioxidante en varones sanos, frente a la hiperglicemia aguda inducida. Diseño: estudio prospectivo, descriptivo, longitudinal, experimental. Lugar: Instituto Nacional de Biología Andina, Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú. Material biológico: Sangre y suero de sujetos aparentemente sanos. Intervenciones: A 13 sujetos adultos clínicamente sanos, entre 20 y 41años, después de 10 horas de ayuno, se administró glucosa vía endovenosa, mediante el método de clamp hiperglicémico, a 125 mg/dL por encima del valor basal, durante 120 minutos. Se realizó mediciones de la glicemia a 0, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 y 120 minutos. Se tomó la muestra sanguínea con anticoagulante EDTA y otra de sangre total, para obtención de suero, para las pruebas bioquímicas a los 0, 60 y 120 minutos. Principales medidas de resultados: Modificaciones de la glicemia y lipoperoxidación en suero, glutatión y actividad superóxido dismutasa en glóbulos rojos lisados e índices de estrés oxidativo. Resultados: El nivel de glucosa durante el clamp hiperglicémico, luego de alcanzar el æequilibrioÆ, fue 197±17,58 mg/dL. La lipoperoxidación aumentó de 2,54 + 0,51 a 2,90 + 0,58 umol/L, de 0 a 60 minutos, y a 2,66 + 0,55 umol/L a los 120 minutos. El glutatión se redujo en 8,10 por ciento a la hora, aumentando 7,08 por ciento a los 120 minutos. La actividad superóxido dismutasa se elevó 0,54 por ciento a los 60 minutos y 5,66 por ciento a los 120 minutos, sobre el basal. Los índices de valoración del estrés oxidativo tuvieron correlación r Pearson positiva, en nivel alto a muy alto. Conclusiones: la hiperglicemia aguda inducida hasta 2 horas elevó el estrés oxidativo, promoviendo generación de defensa antioxidante, con síntesis de glutatión reducido de novo y mayor actividad de la superóxido dismutasa.

Objective: To determine healthy malesÆ antioxidant system response in induced acute hyperglycemia. Design: Prospective, descriptive, longitudinal, experimental study. Setting: National Institute of Andean Biology, Faculty of Medicine, Universidad Nacional Mayor de San Marcos, Lima, Peru. Biological materials: Whole blood and serum of apparently healthy men. Interventions: After 10 hour fasting, intravenous glucose was administered to thirteen healthy 20-41 year-old adult men using the hyperglycemic clamp method at 125 mg/dL above basal value during 120 minutes. Glycemia was measured at 0, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 minutes. Blood sampling was obtained with EDTA anticoagulant and whole blood to obtain blood serum for biochemistry tests at 0, 60 and 120 minutes. Main outcome measures: Blood serum glycemia and lipoperoxidation variation, glutathione and superoxide dismutase activity in lysed red blood cells and oxidative stress index. Results: After achieving æbalanceÆ, glucose levels during hyperglycemic clamp was 197 ± 17,58 mg/dL. Lipoperoxidation increased from 2,54 + 0,51 to 2,90 + 0,58umol/L, from 0 to 60 minutes, and to 2,66 + 0,55 umol/L at 120 minutes. Glutathione was reduced in 8,10 per cent at one hour, rising 7,08 per cent at 120 minutes. Superoxide dismutase activity rose above basal 0,54 per cent at 60 min and 5,66 per cent at 120 min. Oxidative stress valuation index had high level to very high level positive Pearson r correlation. Conclusions: Acute induced hyperglycemia up to 2 hours increased oxidative stress, promoting generation of antioxidant defence with de novo synthesis of reduced glutathione and greater activity of superoxide dismutase.

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It is known that residents at high altitude (HA) have a lower basal glycemia than residents at sea level (SL). However, whether such a difference is maintained throughout the full day remains unknown. We compared 12-h blood glucose profiles from 10 healthy males native residents at HA (3250 m) and 8 male residents at SL. Glucose profile at HA was lower throughout the glucose monitoring than that at SL (mean profile: 50.6 +/- 3.7 and 73.4 +/- 4.0 mg/dL, respectively; p < 0.001). Basal and postprandial insulin and triacylglycerol values were similar in both groups. In conclusion, HA natives resident have a lower blood glucose profile than SL residents throughout 12-h continuous monitoring.

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BACKGROUND: Persons living at high altitude (exposed to hypoxia) have a greater number of coronary and peripheral branches in the heart than persons living at sea level. In this study we investigated the effect of intermittent hypobaric hypoxia on myocardial perfusion in patients with coronary heart disease. METHODS AND RESULTS: We studied 6 male patients (aged>or=53 years) with severe stable coronary heart disease. All patients were born at sea level and lived in that environment. They underwent 14 sessions of exposure to intermittent hypobaric hypoxia (equivalent to a simulated altitude of 4200 m). Myocardial perfusion was assessed at baseline and after treatment with hypoxia by use of exercise perfusion imaging with technetium 99m sestamibi. After the sessions of hypoxia, myocardial perfusion was significantly improved. The summed stress score for hypoperfusion, in arbitrary units, decreased from 9.5+ to 4.5+ after treatment (P=.036). There was no evidence of impairment of myocardial perfusion in any patient after treatment. CONCLUSIONS: Intermittent hypobaric hypoxia improved myocardial perfusion in patients with severe coronary heart disease. Though preliminary, our results suggest that exposure to intermittent hypobaric hypoxia could be an alternative for the management of patients with chronic coronary heart disease.

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